Operators of electrically powered equipment, due to their familiarity with high powered, combustion engine-driven equipment, have become accustomed to and expect nearly instantaneous high power and torque availability when performing work. A mowing deck, for example, typically includes one or more blades which may be directly driven by electric motors.
In many instances, industry expectations dictate that the blade(s) ramp up to an effective cutting speed within approximately two seconds. Substantial torque is required to overcome blade inertia and motion resistance applied to the blade(s) by, for example, thick and/or tall vegetation. Inertia and motion resistance hamper the ability of the relatively small deck motor(s) to ramp up to an effective cutting speed within an operator-perceived acceptable length of time. The addition of these desirable performance features to electric motors typically translates into increased motor sizes and power consumptions, both of which go counter to motor characteristics sought by equipment designers or manufacturers.
Many commercial and consumer mowers often comprise a deck drive system using belts and pulleys driven by a combustion engine and typically utilize an electric clutch/brake to drive and stop the blade(s) of the mowing deck. It would be advantageous to reduce the number of moving parts, which would translate into reduced manufacturing costs, reduced equipment maintenance costs, improved design flexibility, space savings and simplicity in configuring equipment, and weight reduction in some configurations.
Due to their relatively high power capacity, three-phase AC electric motors may be used in utility vehicles or other powered equipment to drive work implements. These electric motors are typically powered by an on-board power source, such as a battery pack or array of batteries. These batteries may be the only source of power or the primary source of power or may be a secondary source of power, depending on vehicle or equipment configuration. In any case, power availability and consumption rate is an increasingly important design concern. AC induction motors, and Permanent Magnet Synchronous (PMS) motors in particular, can be employed advantageously in a variety of utility vehicle applications due to power capacity and their ability to be rapidly accelerated and decelerated.
Therefore, there is a need for an electric motor that includes a clutch/brake assembly having the ability to accelerate and decelerate to targeted speeds within desirable lengths of time, and providing additional benefits to both the operator and manufacturer.